1. Field of the Invention
This invention relates generally to transmitting video data. More particularly, the present invention is directed to transmitting packet information and adjusting a clock frequency.
2. Background Discussion
In order to transmit synchronous data, both frequency and phase must remain constant. For example, two identical crystal oscillators will never have the exact same frequency. Indeed, their relationship may never be constant or determinate. Similarly, the same principle applies to video generated from the oscillators. Typical synchronization techniques require that the clock frequency of the destination match exactly the clock frequency of the source. A standard triple buffering technique uses three frames of video: input frame, idle frame, output frame; and thereby reduces the effect of wandering phase. Unfortunately, this technique has the disadvantage of increased latency. There is typically a 1 to 3 frame delay between the input stream and the output stream if the clocks match very closely. If there is a large difference in the clock frequencies, then some frames of data may be dropped and some frames of data may be displayed multiple times. If a high latency network is used, additional frames of data may need to be buffered to overcome the network pauses. This is a less than desirable approach for an interventional or real-time system where the user is using the video as feed-back for real-time actions, such as computer aided diagnosis (CAD) procedure e.g., the positioning of a catheter in a beating heart.
Therefore, it would be an advancement in the state of the art to provide a system and method that adjust a clock frequency as a function of control data and associated packet data.